1. Field of the Invention
The present invention relates to an information processing system and, more particularly, to an art for monitoring a plurality of components of the same kind (for example, power source units, air cooling fans, and temperature sensors), which are incorporated in an information processing apparatus, to determine if any of the components have malfunctioned.
A plurality of the foregoing components are mounted in an information processing system or the like. In particular, insofar as a system is required to be fault-tolerant is concerned, redundant components are incorporated. A monitor unit for monitoring the components to determine that they are functioning normally is often duplicated. There is a growing demand for an art making it possible to construct such a monitoring system readily and flexibly.
2. Description of the Related Art
FIG. 1 shows the configuration of a prior art state monitoring system. In FIG. 1, reference numerals 90 and 91 denote monitor units. 92 to 96 denote objects to be monitored, such as power source units and fans.
In a known state monitoring system, when a malfunction is detected, each of the objects to be monitored 92 to 96 issues an alarm signal ALM to notify the monitor units 90 and 91 of occurrence of a malfunction. Signal lines linking the objects of monitor 92 to 96 and the monitor units 90 and 91 and each carrying (i.e., conducting) the alarm signal ALM are laid down on a one-to-one basis. In the example of FIG. 1, ten alarm signal ALM lines are laid down.
The monitor units 90 and 91 monitor the objects of monitor 92 to 96 to see if any of the objects transmits the alarm signal ALM. Based on the alarm signal ALM, the occurrence of one fault (a fault occurs in one object of monitor) or the occurrence of a plurality of faults (a fault occurs in each of a plurality of objects of monitor) is detected. The two monitor units 90 and 91 are incorporated, so that in case one of the monitor units 90 and 91 fails, the objects of monitor can be continuously monitored for a malfunction by the other without the need of stopping the state monitoring system.
As shown in FIG. 1, according to the known system configuration in which two monitor units are incorporated, the signal lines for the alarm signal ALM link the objects of monitor 92 to 96 and the monitor units 90 and 91 on a one-to-one basis. Compared with the incorporation of one monitor unit, twice as many signal lines are needed. This results in complex wiring.
For analyzing a faulty state, it is necessary to produce information representing a definition of the patterns of states of signal lines. Each monitor unit is therefore required to carry out complex analyses.
Furthermore, when the number of objects of monitor is changed, for example, when a system is expanded, reconstruction of monitor units becomes necessary. This means that a change in system configuration cannot be coped with flexibly.